Use of computed tomography for evaluation of lung lesions associated with spontaneous pneumothorax in dogs: 12 cases (1999-2002)

OBJECTIVE: To evaluate use of computed tomography (CT) of the lungs, compared with conventional radiography, for detection of blebs and bullae associated with spontaneous pneumothorax in dogs. DESIGN: Retrospective case series. ANIMALS: 12 dogs with spontaneous pneumothorax. PROCEDURE: Medical records were reviewed, and information was collected that included signalment, body weight, initial owner complaint, laboratory findings, radiographic findings, CT findings, medical and surgical treatment, histologic findings, complications, duration of hospitalization, and final outcome. RESULTS: Radiographs were excellent for identifying pneumothorax (sensitivity, 100%) but poor for identifying the underlying cause (bullae or blebs); these were identified in radiographs of only 2 of 12 dogs. Computed tomography allowed identification of bullae or blebs in 9 of 12 dogs. Ten of the 12 dogs were treated via surgery, and 17 affected lung lobes were identified. Four of the 17 affected lobes were identified via radiography. Thirteen of the 17 affected lobes were identified via CT; however, 1 lobe was incorrectly identified as the right caudal lobe instead of the right cranial lobe. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that CT is better than radiography for identifying the underlying causes of spontaneous pneumothorax.     

Retroperitoneal sarcomas in dogs: 14 cases (1992-2002)

OBJECTIVE: To describe the clinical features, surgical and histologic findings, biological behavior, and outcome of dogs with retroperitoneal sarcomas. DESIGN: Retrospective study. ANIMALS: 14 dogs. PROCEDURES: Medical and pathology records from 1992 to 2002 of dogs with tumors originating in the retroperitoneal space were reviewed. Dogs with retroperitoneal tumors originating from the adrenal glands, kidneys, or ureters were excluded. Inclusion criteria included observation of a tumor arising from the retroperitoneal space during exploratory surgery or necropsy and histologic confirmation of tumor type. Details of clinical signs, diagnostic findings, surgical management, and outcome were determined from medical records and telephone interviews with veterinarians and owners. RESULTS: Retroperitoneal sarcoma was diagnosed in 14 dogs, 2 at necropsy and 12 during exploratory surgery. Hemangiosarcoma was the most common histologic diagnosis. Seven dogs had regional extension of the sarcoma into adjacent organs, and 4 dogs had metastatic disease. Grossly complete resection was possible in 6 dogs. Cytoreductive surgery or incisional biopsy was performed in the remaining dogs. Two dogs were treated with palliative radiation therapy (1 intraoperatively and 1 postoperatively). Three dogs received adjunctive chemotherapy, although none completed the targeted course because of development of local recurrence or metastatic disease. Local recurrence was reported in 2 of 12 dogs and metastasis in 10 of 14 dogs. Thirteen dogs died or were euthanatized as a result of the retroperitoneal sarcoma; 1 dog was alive and disease-free 410 days after surgery. Median survival time was 37.5 days. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, retroperitoneal sarcomas are aggressive tumors with a high rate of local recurrence and metastasis, and a poor survival time.     

Classification of primary lung tumors in dogs: 210 cases (1975-1985)

Two hundred ten dogs that had primary lung tumors diagnosed between 1975 and 1985 were evaluated. The majority of the tumors were classified as adenocarcinoma (74.8%) and alveolar carcinoma (20%). The most common clinical signs of disease were cough (52%), dyspnea (23.8%), lethargy (18.1%), weight loss (12.4%), and tachypnea (4.8%). The clinical methods that were most successful in directly or indirectly leading to a diagnosis of primary lung tumor were thoracic radiography (77.1%) and cytologic examination of fine-needle aspirate specimens (24.8%).     

Ultrasonographic findings in dogs with hyperammonemia: 90 cases (2000-2002)

OBJECTIVE: To determine ultrasonographic abnormalities in dogs with hyperammonemia. DESIGN: Retrospective study. ANIMALS: 90 client-owned dogs with hyperammonemia. PROCEDURE: Ultrasonography of the abdominal vessels and organs was performed in a systematic way. Dogs in which the ultrasonographic diagnosis was a congenital portosystemic shunt were included only if they underwent laparotomy or necropsy. Dogs in which the abdominal vasculature appeared normal and dogs in which the ultrasonographic diagnosis was acquired portosystemic shunts and portal hypertension were included only if liver biopsy specimens were submitted for histologic examination. RESULTS: Ultrasonography excluded portosystemic shunting in 11 dogs. Acquired portosystemic shunts were found in 17 dogs, of which 3 had arterioportal fistulae and 14 had other hepatic abnormalities. Congenital portosystemic shunts were found in 61 dogs, of which 19 had intrahepatic shunts and 42 had extrahepatic shunts. Intrahepatic shunts originated from the left portal branch in 14 dogs and the right portal branch in 5. Extrahepatic shunts originated from the splenic vein, the right gastric vein, or both and entered the caudal vena cava or the thorax. Ultrasonography revealed splenic-caval shunts in 24 dogs, right gastric-caval shunts in 9 dogs, splenic-azygos shunts in 8 dogs, and a right gastric-azygos shunt in 1 dog. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that ultrasonography is a reliable diagnostic method to noninvasively characterize the underlying disease in dogs with hyperammonemia. A dilated left testicular or ovarian vein was a reliable indicator of acquired portosystemic shunts.     

Indirect computed tomography lymphangiography with aqueous contrast for evaluation of sentinel lymph nodes in dogs with tumors of the head

Sentinel lymph node evaluation is widely used in human medicine to evaluate the first lymph node(s) to which a tumor drains. Sentinel lymph node biopsy allows avoidance of extensive lymphadenectomies in cases where the sentinel lymph node is negative for metastasis, thereby reducing patient morbidity. It has been shown that regional lymph nodes are not always the sentinel lymph node, thus identification and sampling of sentinel lymph nodes allows for more accurate staging, which is critical for treatment and prognostication in dogs with cancer. The objective of this prospective, pilot study was to determine if indirect computed tomography (CT) lymphangiography with aqueous contrast agent would successfully allow identification of sentinel lymph nodes in dogs with masses on the head. Eighteen dogs underwent CT lymphangiography. The sentinel lymph node was successfully identified within 3 min of contrast injection in 16 dogs (89%). Compression of lymphatic vessels from endotracheal tube ties and/or the patient's own body weight delayed or prevented identification of sentinel lymph nodes in two dogs (11%). Computed tomography lymphangiography with aqueous contrast can be used successfully to rapidly identify sentinel lymph nodes in dogs with masses on the head.     

Correlation of cytologic and histopathologic findings with perinodal echogenicity of abdominal lymph nodes in dogs and cats

Abdominal lymphadenopathy in dogs and cats is routinely investigated with ultrasound. As the determination between benign and neoplastic etiologies of lymphadenopathy affects patient management, specific sonographic characteristics associated with both benign and neoplastic lymph nodes have been suggested. However, a significant overlap between these characteristics exists, necessitating a cytologic or histopathologic diagnosis in most instances. The objectives of this retrospective, cross‐sectional study were to evaluate whether echogenicity of perinodal fat could be a discriminator between benign and neoplastic abdominal lymphadenopathy and to assess if additional sonographic features associated with malignancy could be identified in lymph nodes with hyperechoic perinodal fat. Small animal patients (257 dogs and 117 cats) with sonographic evidence of abdominal lymphadenopathy and a cytological or histopathological diagnosis were evaluated for differences in the proportions of sonographic features between benign and neoplastic groups. Greater maximum long axis diameter (in dogs and cats) and a greater number of abnormal lymph nodes (in cats) were associated with malignancy in lymph nodes with hyperechoic perinodal fat. Canine lymph nodes with round cell neoplasia were significantly more likely to have hyperechoic perinodal fat. Lymph nodes affected with other neoplasia or with lymphadenitis were equally likely to have normal or hyperechoic perinodal fat. Reactive lymph nodes were significantly less likely to have hyperechoic perinodal fat in both species. These results suggest that though echogenicity of perinodal fat is a nonspecific finding, abdominal lymph nodes with hyperechoic perinodal fat are less likely to be reactive and sampling of these lymph nodes may be indicated.     

Samarium Sm 153 lexidronam for the palliative treatment of dogs with primary bone tumors: 35 cases (1999-2005)

OBJECTIVE: To evaluate survival times and palliative effects associated with the use of samarium Sm 153 lexidronam in dogs with primary bone tumors. DESIGN: Retrospective case series. ANIMALS: 35 dogs with primary appendicular (n = 32) or axial (3) bone tumors. PROCEDURES: 1 to 4 doses of samarium Sm 153 lexidronam were administered at a rate of 37 MBq/kg (16.8 MBq/lb), IV. Response to treatment, measured by lameness improvement, and survival time were determined. RESULTS: Of the 32 dogs with appendicular tumors, 20 (63%) had an improvement in the severity of lameness 2 weeks after administration of the first dose of radioactive samarium, 8 (25%) had no change in the severity of lameness, and 4 (12%) had a worsening. Overall median survival time was 100 days, with 3 dogs (8.6%) alive after 1 year. Median survival time for the 32 dogs with appendicular tumors was 93 days, with 3 (9.4%) alive after 1 year. This was not significantly different from the median survival time of 134 days for a historical cohort of 162 dogs with appendicular osteosarcoma that underwent amputation as the only treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that samarium Sm 153 lexidronam may be useful in the palliation of pain in dogs with primary bone tumors that are not candidates for curative-intent treatment.     

Angiostrongylus vasorum infection in 23 dogs (1999-2002)

Angiostrongylosis was diagnosed in 23 dogs presenting to the Queen Mother Hospital for Animals between June 1999 and August 2002. The animals' clinical records were reviewed retrospectively and certain risk factors were compared with a control population of 3407 dogs. Twenty-two of the 23 dogs were from south-east England and dogs from Surrey (n=8) were significantly overrepresented. There were also significantly more Cavalier King Charles spaniels (n=5) and Staffordshire bull terriers (n=5) among the affected dogs than in the control group. The median age of affected dogs was 10 months (range five to 90 months). The most common presenting signs were cough (65 per cent), dyspnoea (43 per cent), haemorrhagic diathesis (35 per cent) and collapse (26 per cent). Four dogs were thrombocytopenic and eight had significant prolongations in prothrombin time and/or activated partial thromboplastin time. Thoracic radiographs were abnormal in 18 of 19 dogs. A variety of changes were observed, the most typical being a patchy alveolar-interstitial pattern affecting the dorsocaudal lung fields. Angiostrongylus vasorum larvae were found in seven of 10 bronchoalveolar lavage specimens and 19 of 19 faecal samples. Three dogs died shortly after admission to the hospital. The remainder were successfully treated with fenbendazole at a dose of 50 mg/kg for five to 21 days. A vasorum should now be considered endemic to south-east England.     

Clinical features of epistaxis in dogs: a retrospective study of 35 cases (1999-2002)

Epistaxis was retrospectively evaluated in 35 dogs. Systemic disease was diagnosed in seven dogs and intranasal disease in 29. Nineteen dogs with intranasal disease had neoplasia. Dogs with neoplasia were older (mean 10.0 years) than dogs with nonneoplastic intranasal disease (mean 5.6 years). Signs persisting for >1 month occurred more often in dogs with intranasal than systemic disease. Unilateral epistaxis did not distinguish intranasal from systemic disease. Only dogs with intranasal disease had facial deformity, decreased airflow, or regional sub-mandibular lymphadenopathy. Dogs with systemic disease had a lower packed cell volume (mean 31.8%) than dogs with intranasal disease (mean 42.7%).     

Clinicopathological findings and results of bone marrow aspiration in dogs with cutaneous mast cell tumours: 157 cases (1999–2002)*

Bone marrow aspiration for routine staging of canine cutaneous mast cell tumour is not consistently performed, and the overall incidence of bone marrow infiltration and predictive value of the complete blood count (CBC) is unknown. This study evaluated a series of 157 dogs presented for cutaneous mast cell tumours in which a CBC and bone marrow aspiration were performed. The incidence of bone marrow infiltration at initial staging was low at 2.8%, and 4.5% overall. Factors significantly associated with bone marrow infiltration included increased age, leucocytosis, anaemia, neutrophilia, monocytosis, eosinophilia, thrombocytopenia, being purebred and staging at the time of recurrent or progressive disease. Our study suggests that a bone marrow sample is not indicated for routine staging but maybe indicated for those dogs with mast cell tumours having either an abnormal haemogram (neutrophilia, monocytosis, eosinophilia, basophilia, anaemia and thrombocytopenia) or presenting for tumour regrowth, progression or new occurrence.     

Streptozocin for treatment of pancreatic islet cell tumors in dogs: 17 cases (1989-1999)

OBJECTIVE: To determine toxic effects of streptozocin given in combination with a diuresis protocol in dogs and establish whether streptozocin is efficacious in treatment of pancreatic islet cell tumors in dogs. DESIGN: Retrospective study. ANIMALS: 17 dogs. PROCEDURE: Medical records were reviewed to obtain information regarding signalment, tumor stage and staging tests performed, number of streptozocin treatments, adverse effects, results of biochemical and hematologic monitoring during streptozocin treatment, tumor dimensions, duration of normoglycemia, and date of death, when applicable. Dogs were compared with a historical control group of 15 dogs treated surgically and medically. RESULTS: 58 treatments were administered to the 17 dogs. Only 1 dog developed azotemia. Serum alanine aminotransferase activity increased in some dogs but decreased when treatment was discontinued. Hematologic toxicoses were rare. Vomiting during administration was uncommon but occasionally severe. Two dogs developed diabetes mellitus after receiving 5 doses. Median duration of normoglycemia for 14 dogs with stage-II or -III insulinoma treated with streptozocin was 163 days (95% confidence interval, 16 to 309 days), which was not significantly different from that for the control dogs (90 days; 95% confidence interval, 0 to 426 days). Two dogs had rapid resolution of paraneoplastic peripheral neuropathy, and 2 others had measurable reductions in tumor size. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that streptozocin can be administered safely to dogs at a dosage of 500 mg/m2, IV, every 3 weeks when combined with a protocol for induction of diuresis and may be efficacious in the treatment of dogs with metastatic pancreatic islet cell tumors.     

Correlation between leukocytosis and necropsy findings in dogs with immune-mediated hemolytic anemia: 34 cases (1994-1999)

OBJECTIVE: To determine whether severity of leukocytosis correlates with severity of postmortem lesions in dogs with immune-mediated hemolytic anemia (IMHA). DESIGN: Retrospective study. ANIMALS: 34 dogs with IMHA that had CBC performed within 48 hours prior to death and complete necropsy examinations. PROCEDURE: Dogs were independently assigned to 4 leukocytosis groups (within reference range; mild leukocytosis, moderate leukocytosis, marked leukocytosis) and 3 lesion severity groups (mild lesions, moderate lesions, severe lesions). RESULTS: Moderate to marked leukocytosis correlated with moderate to severe postmortem lesions. Ischemic necrosis within liver, kidney, heart, lung, and spleen attributable to thromboembolic disease or anemic hypoxia were the most common important lesions found at necropsy. None of the dogs with mild lesions had moderate or marked leukocytosis. Four of 14 severely affected dogs had WBC counts within reference range, but all 4 had neutrophilic left shifts. Three of these 4 dogs had toxic change in neutrophils. CONCLUSION AND CLINICAL RELEVANCE: Moderate to marked leukocytosis, neutrophilic left shift, and toxic change in neutrophils in dogs with IMHA should alert clinicians to the potential for moderate to severe tissue injury, which could complicate treatment and worsen prognosis. Lesions appear to be secondary to anemic hypoxia, thromboembolic disease, or both; therefore, treatment objectives should focus on improving blood oxygen-carrying capacity and monitoring for thromboembolic disease.     

Pretreatment clinical and laboratory findings in dogs with primary hyperparathyroidism: 210 cases (1987-2004)

OBJECTIVE: To evaluate pretreatment clinical and laboratory findings in dogs with naturally occurring primary hyperparathyroidism. DESIGN: Retrospective study. ANIMALS: 210 dogs with primary hyperparathyroidism and 200 randomly selected, age-matched control dogs that did not have primary hyperparathyroidism. PROCEDURE: Medical records for dogs with primary hyperparathyroidism were reviewed for signalment; clinical features; and results of clinicopathologic testing, serum parathyroid hormone assays, and diagnostic imaging. RESULTS: Mean age of the dogs with primary hyperparathyroidism was 11.2 years (range, 6 to 17 years). The most common clinical signs were attributable to urolithiasis or urinary tract infection (ie, straining to urinate, increased frequency of urination, and hematuria). Most dogs (149 [71%]) did not have any observable abnormalities on physical examination. All dogs had hypercalcemia, and most (136 [65%]) had hypophosphatemia. Overall, 200 of the 210 (95%) dogs had BUN and serum creatinine concentrations within or less than the reference range, and serum parathyroid hormone concentration was within reference limits in 135 of 185 (73%) dogs in which it was measured. Urolithiasis was identified in 65 (31 %) dogs, and urinary tract infection was diagnosed in 61 (29%). Mean serum total calcium concentration for the control dogs-was significantly lower than mean concentration for the dogs with primary hyperparathyroidism, but mean BUN and serum creatinine concentrations for the control dogs were both significantly higher than concentrations for the dogs with primary hyperparathyroidism. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that urolithiasis and urinary tract infection may be associated with hypercalcemia in dogs-with primary hyperparathyroidism, but that development of renal insufficiency is uncommon.     

Treatment of chronic pleural effusion with pleuroperitoneal shunts in dogs: 14 cases (1985-1999).

OBJECTIVE: To describe complications and outcome associated with chronic nonseptic pleural effusion treated with pleuroperitoneal shunts in dogs. DESIGN: Retrospective study. ANIMALS: 14 dogs. PROCEDURE: Medical records at 4 veterinary schools were examined to identify dogs with chronic nonseptic pleural effusion that were treated by use of a pleuroperitoneal shunt between 1985 and 1999. Signalment, history, physical examination and laboratory findings, cause and type of pleural effusion, medical and surgical treatments, complications, and outcome were reviewed. RESULTS: 10 of 14 dogs had idiopathic chylothorax, and 4 had an identified disease. All but 1 dog with idiopathic chylothorax and 1 dog with chylothorax from a heart base tumor had unsuccessful thoracic duct ligation prior to pump placement. No intraoperative complications developed during shunt placement. Short-term complications developed in 7 of 13 dogs, necessitating shunt removal in 2 dogs and euthanasia in 1. Eight of 11 dogs with long-term follow-up developed complications; the overall mean survival time and the interval in which dogs remained free of clinical signs of pleural effusion were 27 months (range, 1 to 108 months) and 20 months (range, 0.5 to 108 months), respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Pleuroperitoneal shunts can effectively palliate clinical signs associated with intractable pleural effusion in dogs. Numerous short- and long-term complications related to the shunt should be expected. Most complications can be successfully managed, but even when shunts are functional some treatments fail because of severe abdominal distension or massive pleural fluid production that overwhelms the functional capacity of the shunt.     

Radiotherapy-induced myelosuppression in dogs: 103 cases (2002-2006)

Definitive radiotherapy refers to delivery of large doses, typically 48-62 Gray, of ionizing radiation over several weeks using a daily or alternate-day fractionation schedule. The impact of definitive radiotherapy alone on haematopoiesis in tumour-bearing dogs is unknown. Medical records from 103 dogs receiving definitive (60) Cobalt teletherapy for cancer over a 5-year period were reviewed for signalment, tumour type and location, total radiotherapy dose and fractionation scheme. Complete blood count data were collected before, halfway through, and at the end of radiation treatment, and analysed for changes associated with patient variables. The results demonstrate significant reductions in haematocrit, total white blood cell count, neutrophils, eosinophils, monocytes, lymphocytes and platelets occurred during definitive radiotherapy but remained within laboratory reference intervals. These data are important for anticipation of toxicity associated with combinations of radiotherapy and chemotherapy in dogs but do not support the routine monitoring of haematology parameters during definitive radiotherapy.     

Gallbladder mucocele in dogs: 30 cases (2000-2002)

OBJECTIVE: To determine long-term outcome of dogs with gallbladder mucocele. DESIGN: Retrospective study. ANIMALS: 30 dogs with gallbladder mucocele, including 23 that underwent cholecystectomy. PROCEDURE: Medical records were reviewed for signalment, history, and clinical, ultrasonographic, and surgical findings. Follow-up information was obtained for all dogs that survived the perioperative hospitalization period. RESULTS: 23 dogs had signs of systemic illness; 7 had no clinical signs. Median values for serum activities of alanine aminotransferase and alkaline phosphatase, serum total bilirubin concentration, and total WBC count were significantly higher among dogs with gallbladder rupture than among dogs without rupture. Sensitivity of sonography for detection of rupture was 85.7%. Overall perioperative mortality rate for dogs that underwent cholecystectomy was 21.7%; mortality rate was not significantly greater for dogs with rupture. Aerobic bacteria were isolated from the bile or gallbladder wall in 8.7% of dogs. All 18 dogs discharged from the hospital had complete resolution of clinical signs. In dogs that underwent in-hospital reexamination, serum liver enzyme activities were significantly decreased, compared with preoperative activities. Persistent increases in serum activities of 1 or more liver enzymes were detected in 9 of 12 dogs; 6 of 12 dogs had persistent abnormalities in hepatic echogenicity. Mean follow-up period was 13.9 months. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that cholecystectomy is an effective treatment for gallbladder mucocele. Although perioperative mortality rate is high, prognosis after discharge from the hospital is excellent. Rupture of the gallbladder warrants emergency surgical intervention but does not preclude a positive outcome.     

Assessment of survey radiography and comparison with x-ray computed tomography for detection of hyperfunctioning adrenocortical tumors in dogs

Results of abdominal survey radiography and x-ray computed tomography (CT) were compared in 13 dogs with hyperadrenocorticism histologically attributed to adrenocortical tumors. X-ray computed tomography enabled accurate localization of the tumor in all 13 dogs. Apart from 2 poorly demarcated irregular-shaped and mineralized carcinomas, there were no differences between adenoma (n = 3) and carcinoma (n = 10) on CT images. In 1 dog, invasion of the caudal vena cava by the tumor was suggested on CT images and was confirmed during surgery. Suspicion of adhesions between tumors of the right adrenal gland and the caudal vena cava on the basis of CT images was confirmed during surgery in only 2 of 6 dogs. Survey radiography allowed accurate localization of the tumor in 7 dogs (4 on the right side and 3 on the left). In 6 of these dogs, the tumor was visible as a well-demarcated soft tissue mass and, in the other dog, as a poorly demarcated mineralized mass. The smallest tumor visualized on survey radiographs had a diameter of 20 mm on CT images. Six tumors with diameter less than or equal to 20 mm were not visualized on survey radiographs. In 1 of these dogs, a mineralized nodule was found in the left adrenal region, without evidence of a mass. In a considerable number of cases, survey radiography can provide presurgical localization of adrenocortical tumors in dogs with hyperadrenocorticism; CT is redundant in these instances. In the absence of positive radiographic findings, CT is valuable for localization of adrenocortical tumors.